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2 weeks ago

I have the following data set, I am trying to select only observations

with at least 1 positive and 1 negative outcome.

```
Data Diagnose;
Input @1 Patient_No $2.
@3 Date MMDDYY10.
@14 Visit_No $2.
@16 Outcome $12.;
Format Date MMDDYY10.;
Datalines;
1 10/21/2000 1 Positive
1 10/25/2000 2 Positive
1 11/01/2000 3 Negative
1 05/28/2001 4 Negative
2 11/22/2000 1 Positive
2 11/29/2000 2 Positive
2 12/28/2000 3 Positive
2 06/28/2001 4 Low positive
2 10/29/2001 5 Negative
3 12/12/2000 1 Positive
3 12/29/2000 2 Positive
3 02/21/2001 3 Positive
3 07/12/2001 4 Negative
3 08/29/2001 5 Positive
4 08/29/2001 1 Positive
4 09/05/2001 2 Positive
4 11/01/2001 3 Positive
;
run;
```

I tried the following code.

data a;

set diagnose;

where outcome = "Positive" and "Negative";

proc print;

run;

Accepted Solutions

Solution

2 weeks ago

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Posted in reply to PGStats

2 weeks ago

Yes, that works. Thank you for the addition of patient no 5.

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Posted in reply to nerdy2703

2 weeks ago

Beware of the cases where there are more than one distinct outcome but only one of them is Positive or Negative (patient_no = 5 below) :

```
Data Diagnose;
Input @1 Patient_No $2.
@3 Date MMDDYY10.
@14 Visit_No $2.
@16 Outcome $12.;
Format Date MMDDYY10.;
Datalines;
1 10/21/2000 1 Positive
1 10/25/2000 2 Positive
1 11/01/2000 3 Negative
1 05/28/2001 4 Negative
2 11/22/2000 1 Positive
2 11/29/2000 2 Positive
2 12/28/2000 3 Positive
2 06/28/2001 4 Low positive
2 10/29/2001 5 Negative
3 12/12/2000 1 Positive
3 12/29/2000 2 Positive
3 02/21/2001 3 Positive
3 07/12/2001 4 Negative
3 08/29/2001 5 Positive
4 08/29/2001 1 Positive
4 09/05/2001 2 Positive
4 11/01/2001 3 Positive
5 11/22/2000 1 Low positive
5 11/29/2000 2 Negative
5 12/28/2000 3 Negative
5 06/28/2001 4 Negative
;
proc sql;
create table a as
select *
from diagnose
group by patient_no
having count( distinct
case outcome
when "Positive" then 1
when "Negative" then 2
else . end ) > 1
order by patient_no, visit_no;
select * from a;
quit;
```

PG

Solution

2 weeks ago

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Posted in reply to PGStats

2 weeks ago

Yes, that works. Thank you for the addition of patient no 5.

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Posted in reply to nerdy2703

2 weeks ago

For a non SQL solution:

```
data b;
do until(last.patient_no);
set diagnose; by patient_no notsorted;
pos = pos or outcome = "Positive";
neg = neg or outcome = "Negative";
end;
do until(last.patient_no);
set diagnose; by patient_no notsorted;
if pos and neg then output;
end;
drop pos neg;
run;
proc print noobs; run;
```

PG

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Posted in reply to PGStats

2 weeks ago

@ PGStats, can you explan how does this code works?

pos = pos or outcome = "Positive";

I tried below, and it does not work.

pos = (outcome = "Positive");

pos = pos or outcome = "Positive";

I tried below, and it does not work.

pos = (outcome = "Positive");

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Posted in reply to SAS_inquisitive

2 weeks ago

Simple logic. At the start of a patient obs, pos is missing which is interpreted as False. The logic expression ensures that at each iteration over the visits of a patient, if pos is already True, it remains True (True OR <*anything*> = True), otherwise it becomes true if outcome="Positive".

Thus, after iterating over a patients' visits, pos = True if "Positive" was met at least once.

PG

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Posted in reply to nerdy2703

2 weeks ago

Since there's only one outcome value in your observations, it can never be positive and negative at the same time.

Define what you consider an "observation"; in SAS speak, an observation is a single row of data in a dataset.

---------------------------------------------------------------------------------------------

Maxims of Maximally Efficient SAS Programmers

Maxims of Maximally Efficient SAS Programmers

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Posted in reply to KurtBremser

2 weeks ago

Yes, but the above example is transposed and ordered, should have pointed that out.